Light source device and projection display

• US 7,070,281 B2
• Filed: 11/25/2003
• Issued: 07/04/2006
• Est. Priority Date: 12/04/2002
• Status: Expired due to Fees

• Current Assignee: NEC Display Solutions, Ltd. (NEC Corporation)
• Original Assignee: NEC Viewtechnology, Ltd. (NEC Corporation)
• Inventors: Kato, Atsushi
• Primary Examiner(s): Dowling, William C.
• Application Number:
  US10/720,104
• Publication Number:
  US 20040109329A1
• Time in Patent Office: 952 Days
• Field of Search: 353/20, 353/31, 353/33, 353/34, 353/37, 353/94, 349/5, 349/7, 349/8, 349/9, 362/231, 345/39, 345/44, 345/46, 345/82, 348/742, 348/743, 348/771, 359/634
• US Class Current: 353/20
• CPC Class Codes: H04N 9/315 Modulator illumination systems general applications of lighting devices F21V; general optical systems G02B; lamp houses for projectors not peculiar to the presence of an electronic spatial light modulator G03B21/20

Abstract

A light source device which employs a plurality of light emitting diodes for emitting different colors of light, and a projection display which incorporates the light source device provide for a good white balance and a high light utilization efficiency in consideration of light emission efficiencies inherent to the respective color light emitting diodes. An illumination beam from each of light emission boards is converted to one type of polarized light respectively by associated polarized light forming means, and resulting polarized light beams are combined by a polarizing beam splitter to produce an illumination beam for illuminating a two-dimensional image device which may comprise a digital mirror device (DMD). The light emitting diodes in the respective colors are arranged on respective light emission boards in a predetermined ratio of distribution to optimize the white balance.

Claims

1. A light source device comprising:

at least two light emission boards that each have light emitting diodes that emit red, green, and blue light;

polarized light formers that each oppose a respective different one of said light emission boards and that receive respective beams of randomly polarized light emitted from said light emitting diodes, at least one of said polarized light formers converting the respective beam to a first type of linearly polarized light and at least one of said light formers converting the respective beam to a second type of linearly polarized light orthogonal to the first type, said polarized light formers emitting polarized light beams therefrom; and

a V-shaped polarized light combiner with two light receiving surfaces at 45°

to optical axes of the incident polarized light beams, said light receiving surfaces transmitting or reflecting the polarized light beams incident thereon depending on the type of the polarized light, said combiner combining the incident polarized light beams into a single direction for emission therefrom.

2. The light source device according to claim 1, wherein said combiner comprises a wire grid type polarizer.

3. The light source device according to claim 1, further comprising beam lens arrays disposed between respective pairs of said light emission boards and said polarized light formers.

4. The light source device according to claim 1 in a projector having a digital mirror that modulates light emitted from the device to generate a projection image.